An electrostatic paint spraying system is a system in which an earthed workpiece and a paint sprayer are provided, as positive and negative electrodes respectively, and an electric field is generated between the electrodes to efficiently attach atomized and negatively charged paint to the workpiece. Recently, in the field of electrostatic paint spraying systems, aqueous paints are increasingly used. When an aqueous paint is used in an electrostatic paint spraying system, in order to prevent the voltage charge on the paint in the paint sprayer from transmitting to a paint source through the conductive aqueous paint, a voltage block device is disposed between the paint source and the paint sprayer. Japanese Unexamined Patent Publication No. 6-198228 discloses an example of such a voltage block device.
On the other hand, another electrostatic paint sprayer, which employs an external electrode, is known. The external electrode discharges electricity to generate an ionized region in which the paint particles pass and are charged, instead of directly charging the particles, so that the particles move along the electric lines of flux (electric field) to attach to a coating object. Japanese Unexamined Patent Publication No. 7-213958 discloses an example of an indirect-charging electrostatic paint sprayer composed of a spray gun and an external electrode.